Can a person be in Investor VISA and work at some other company?

No

@AlienCast

Investor never need to work as employee.

But Investor can do business with any company and take money from other company.

Via contracts.

What OP is asking is, if, an investor can work as an employee for another company?  The answer is no.

@XTang Exactly.

Employment visas and investor visas are different. Employment visa holders shall not do business and investor visa holders shall not be employed.

Could they work freelance at another company in the same industry though

Maybe 3 or 4 times a month ?

@expatbahrain123

I do not know the regulations related to freelance or volunteer work in Bahrain. But an investor  shall not be in an employee pay payroll for sure

Could they work freelance at another company in the same industry though
Maybe 3 or 4 times a month ?
-@expatbahrain123

No. 

@expatbahrain123

legally he can't work. Investor visa itself for business, not for employee.

But as a businessman he can provide service to that company and for that he can visit client office so many times in a month and provide service and take money in Company account not in personal.

And, he needs to have contracts between his company and the company he is visiting so that if LMRA check, he is there to provide a contracted service.

Why does he want to visit the office? In anycase being an investor doesn't entitle one to work for someone else on freelance basis.

What he is saying is that he wants to do freelance work for another company.

Legally, he cannot do that.  No confusion on that.

The only way, he can do that and be present in that office is IF:

1) His company signs a contract for service provision with that other company

2) And he ends up being the contractor or company reprepsentative on site doing that

3) The payment is to his company and not him

Hi Xtang just to update you, I applied for employment Visa in Bahrain and was rejected twice, my employer contacted Immigration and he was given 1 form and 2 documents to fill out and submit. I hope nothing is wrong do you think I will be approved?

Just wait and see.

@XTang

I think you might be wrong, If you have a CR you can work for a company on an ad hoc basis surely, otherwise what is the point of starting a company here